There are 7.6 million residents in the nine-county San Francisco Bay Area, about 5.4 million of them live in San Mateo, Santa Clara, Alameda and Contra Costa counties.
That’s based on new figures released earlier this month by the U.S. Census Bureau in its American Community Survey. Compiled between 2013 and 2017, the new figures provide one of the most detailed views available of the region’s economy and population. Here are a few of the most interesting findings about Alameda, Contra Costa, San Mateo and Santa Clara counties.
Population
Santa Clara County’s 1.9 million residents make it the largest in the region, beating out second ranked Alameda County by about 300,000 people. And Santa Clara is growing — its population is up 9.9 percent from 2010.
With a median age of 37, Santa Clara and Alameda are also the youngest counties in the Bay Area. The median age in California is 36.
Race and ethnicity
Since 2015, Hispanics have outnumbered whites in California as a whole. But among Alameda, Contra Costa, San Mateo and Santa Clara counties, whites outnumber every other ethnic and racial group in every county but one. Asians make up 35 percent of Santa Clara County’s population, edging out whites who make up 33 percent. The county also has the largest Hispanic population of the four, at 26 percent.
Contra Costa County has the smallest Asian population among the four, at 16 percent. That’s close to California’s overall 14 percent Asian population.
Black residents are the fourth largest group, but their highest share of the population, in Alameda County, is 11 percent. There are more individuals self-identifying as being of two or more races in San Mateo and Santa Clara counties — 3.7 and 3.1 percent respectively — than the percentage of African-Americans in either county.
Foreign born
Santa Clara County has the largest foreign-born population among the four counties, with about 39 percent of its residents born outside the U.S. (The figure includes naturalized U.S. citizens.) Among Santa Clara’s foreign-born residents, 61 percent are Asian, 23 percent are Hispanic and 13 percent are non-Hispanic white.
At 25 percent, Contra Costa had the smallest share of foreign-born residents, lower than California’s overall 27 percent.
Not surprisingly, Santa Clara also has the highest share of residents 5 years and older who speak a language other than English at home. At 52 percent, that’s higher than California’s overall 44 percent. Asian and Pacific Island languages are the most common, other than English, at 24 percent, followed by Spanish at 18 percent.
Housing
Alameda, Contra Costa, San Mateo and Santa Clara all had vacancy rates below 5 percent, lower than California’s 8 percent. They differed more on the types of homes available. About 75 percent of homes in Contra Costa are single family units, either attached or detached. In Alameda County, that number is 61 percent.
But Alameda has the oldest homes: About 20 percent of homes there were built in 1939 or earlier, twice the state’s rate.
Contra Costa residents seem to be staying in their stand-alone homes, because 66 percent of them are owner occupied. For those who rent, the cheapest option among the four counties might be Alameda, which has a median rent of $1,547 — about $200 more expensive than California’s median, according to the census. San Mateo County has the most expensive rental market, with median rent of $1,973.
